first law of thermodynamics first law of motion • first lieutenant · · · Info · Definitions · Synonyms · Characters · · first law of thermodynamics · · Text Common · · Latin · · Scripts 27 · · Length 8 · · Syllables Definitions · · · (noun) the fundamental principle of physics that the total energy of an isolated system is constant despite internal changes. Synonyms: conservation of energy, law of conservation of energy, first law of thermodynamics. · · Noun Definition 1 Synonyms · · · conservation of energy · · Synonym 1 law of conservation of energy · · Synonym 2 Characters · · space U+0020 a latin small letter a U+0061 c latin small letter c U+0063 d latin small letter d U+0064 e latin small letter e U+0065 f latin small letter f U+0066 h latin small letter h U+0068 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074 w latin small letter w U+0077 y latin small letter y U+0079